1. The Field of the Invention
The present invention relates generally to methods for treating periodontal disease, particularly to methods that utilize laser energy to destroy necrotic tissue and bacteria that have been stained with an appropriate dye.
2. The Relevant Technology
It is well known that periodontal disease is caused by bacteria that grows and festers within the periodontal pocket. Porphyromonas gingivalis and other bacteria host not only in the soft tissue around the periodontal pocket, but also in plaque that is formed on the surface of the tooth. If left untreated, such bacteria can cause swelling of the gingiva, pain and possible loss of the tooth. Surrounding gums and teeth can also become infected.
In the conventional treatment of periodontal disease, instruments are inserted into the periodontal pocket to mechanically debride the plaque from the tooth and also to remove the necrotic soft tissue by curettage. Antibiotics may also be conventionally placed in the periodontal pocket following such conventional treatment to ensure complete eradication of the infection and to combat reinfection.
Even with conventional debridement and curettage of the periodontal pocket, it is well known that subsequent bacterial infections of the periodontal pocket following treatment are common and can recur relatively soon after treatment. This is particularly true since the patient may not exercise proper dental care following the treatment for the periodontal disease. Consequently, such subsequent bacterial reinfection of the periodontal pocket may often necessitate further debridement of hard and soft tissue from the periodontal pocket.
Chemical therapies have also been used to treat periodontitis and other infections of the periodontal pocket. Such treatments require the application of high concentrations of an antimicrobial agent for hours or days. The drawback of chemical therapies is that they do not result in the physical removal of necrotic and infectious tissues and have not been shown to completely heal the problem area. They cannot remediate the problem of detached gingiva and cannot eliminate the presence of the periodontal pocket. In addition, bacterial strains can develop resistance to chemical antibiotics, and their use can disrupt the microflora of the oral cavity and the gastrointestinal tract, leading to secondary infections by opportunistic microbials.
In extreme cases, periodontal flap surgery has been used, but this technique involves cutting, cleaning, sewing, and reattaching the gingival tissue to the tooth surface. This technique is highly invasive, expensive, and painful, and requires considerable time to heal.
More recently, less intrusive techniques involving the use of lasers have been developed, although such processes can damage surrounding gum and hard tissue in an effort to completely remove the infecting bacteria and diseased tissue. In general, laser techniques are not sufficiently selective and the laser equipment can be quite expensive. One such technique, as taught by U.S. Pat. No. 6,019,605 to Myers, involves irradiation of the soft tissue and plaque with high power laser light, followed by conventional debridement and curettage of the periodontal pocket, followed by reirradiating the tissue and plaque with high power laser light.
Another laser technique, as taught by U.S. Pat. No. 5,611,793 to Wilson, involves the application of a photosensitizing compound to the infected area such that the infecting bacteria are stained by the compound and then irradiating the area with laser light at a wave length absorbed by the photosensitizing compound in order to destroy the infecting bacteria. One drawback of Wilson is that Wilson only discloses the use of lasers that emit wavelengths at the red end of the spectrum or longer, some of which are quite expensive. Longer wavelengths have been found to penetrate deeply into tissue, with the result being that their exclusive use can result in damage to surrounding or underlying tissues. Increased pain and a slower recovery may result from the use of such lasers. Another drawback is that some of the photosensitizing compounds disclosed in Wilson are known to be carcinogenic or otherwise harmful.
In view of the foregoing, it would be an advancement in the art to provide new photosensitizing compositions and lasers for use in treating periodontal disease that addressed the foregoing drawbacks. In particular, it would be an advancement to provide lower cost lasers that could be used to treat periodontal disease. In would be an additional advancement to provide lasers that emitted at appropriate wavelengths in order to limit the depth of penetration of the laser energy in order to better focus and restrict the tissue-destroying action of the laser energy. In would yet be an advancement in the art to provide photosensitizing compositions that maximized the absorption of the improved lasers of the present invention, particularly if such compositions were not carcinogenic or dangerous to use.
Methods which utilize photosensitizing compositions and lasers in treating periodontal disease are disclosed and claimed herein.
The present invention involves methods for treating periodontal disease in the periodontal pocket by destroying the infecting bacteria and removing necrotic tissue with less pain, less risk of damage to surrounding tissues, and lower cost compared to the prior art. Such methods involve the use of appropriate dye compositions in order to stain the infecting bacteria and necrotic tissue. Stained tissues much more readily absorb the light energy emitted by the laser. This allows for the efficient and accurate thermal destruction, disinfecting and ablation of the bacteria and necrotic tissue by means of laser energy.
In brief, contacting the infected and surrounding necrotic tissues with a staining dye system treats and prepares the targeted tissue and bacteria within the periodontal pocket for the laser irradiation step. The targeted tissues and bacteria absorb the dye, thus becoming stained and sensitized to the laser""s output wavelength(s). A laser that outputs one or more wavelengths absorbed by the dye system is then used to irradiate the stained area. The targeted tissues are thereby destroyed and the infecting bacteria killed as the stained issue more strongly absorbs the energy contained within the laser light compared to surrounding tissues that are not stained. Absorption of the laser energy causes the stained tissue and bacteria to quickly heat up and vaporize and/or become denatured and detached from the surrounding healthy tissues so as to form a coagulate and/or char.
In a preferred composition according to the invention, the dye composition includes a red-orange water-based dye within a carrier liquid. The dye composition may optionally include one or more antibiotics, anesthetics, flavorants, or additional dye components. In the preferred method of the invention, a laser that strongly emits in the blue-green region of the spectrum is used in combination with the preferred dye composition, preferably by means of a fiber optic strand or tip that carries the laser light energy to the target site. An example of such a laser is an argon laser. Of course it will readily be understood that the use of any laser that strongly emits one or more wavelengths of light in a range of about 450 nm to about 600 nm is within the scope of the invention.
Because of the dye composition""s light absorption characteristics, it absorbs the laser light, which selectively heats and destroys the stained bacteria and surrounding necrotic tissue, thus forming a coagulate and/or char. The coagulate or char formed by the procedure is removed as it adheres to the fiber tip of the laser by simply removing and cleaning the fiber tip as needed. Depending on the size of the diseased area, it may be necessary to remove and insert the fiber tip a number of times in order to remove all of the coagulate or char formed during destruction of the bacteria and necrotic tissue. Removal and insertion of the fiber tip may also serve to score (i.e., damage) the freshly exposed tissue, thus stimulating growth and readhesion of the tissue to the tooth.
The argon or other laser emitting in a range of about 450 nm to about 600 nm may either be used alone or in combination with a laser diode that emits in the IR region (e.g., 810 nm) in order to provide additional and complementary heating characteristics. In the case where a dual or multi-wavelength system is employed, it may be advantageous to include a dye system that includes two or more dyes that are able to collectively absorb each of the wavelengths being emitted. In the case where a multi-wavelength laser device is used that emits in the IR region, it may be useful to include one or more naphthalocyanines, which absorb strongly in the 750-850 nm range.
The use of the dye composition to target certain areas within the periodontal pocket results in a lower laser power requirement to kill the infecting bacteria (as compared to the prior art) because the formula enhances the absorption characteristics of the infected tissue at the wavelength of the laser. In addition, the relatively shorter wavelengths (i.e., high frequencies) of light emitted in the region of about 450 nm to about 600 nm penetrate less deeply into tissue compared to laser energy at longer wavelengths, thereby further pinpointing the tissue-destroying activity of the laser energy. Because of the lower laser power requirement, as well as the more focused tissue-destroying effect using the laser energy disclosed herein, there is less risk of damage to surrounding soft and hard tissue, less pain during and after surgery, and healing of the gingival tissue occurs faster than it otherwise would. In addition, the controlled damage that does occur to surrounding tissue is beneficial because the use of the laser on the infected soft tissue creates a new adjacent soft tissue surface that can readhere to the tooth, thereby closing the periodontal pocket. Furthermore, the preferred photosensitizing formula is not carcinogenic or otherwise harmful to the patient.
These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.